I understand why pcv systems are essential, but I am curious to know what the purpose of the little mesh canister is. I noticed it when I did a bunch of work on the cooling system, I took that little pipe off and painted it since i was painting other bits too. The little canister had some gunk built up on it which i cleaned before putting it back. Interestingly the gunk was on top which is the opposite direction of flow so that was a little odd.

 

The mesh is a simple oil/air separator. The oil vapor collects on it and it drains back into the engine vs getting sucked into the intake. They should be kept very clean, as blockage pressurizes the crankcase, and blows oil past gaskets and seals

 

Interesting. At what intervals should that be cleaned as a matter of maintenance?